Crane safe load indicator



June 3, 1969 12J. DALY CRANE SAFE LOAD INDICATOR Sheet Filed April l2. 1967 June 3, 1969 T. J. DALY CRANE SAFE LOAD INDICATOR sheet Z Filed April 12, 1957 bwl ww TMm/1s J. 9,4m/

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United States Patent O 3,447,368 CRANE SAFE LOAD INDICATOR Thomas J. Daly, 447 Alcyon Blvd., Pitman, NJ. 08071 Filed Apr. 12, 1967, Ser. No. 630,273

Int. CL G01l 5/12 US. Cl. 73 144 5 `Claims ABSTRACT OF THE DISCLGSURE This invention relates to a crane safe load indicator. More particularly, this invention relates to a tensiometer and supporting apparatus which allows it to be positioned on the crane in operative association with the cable which forms the main hoist line for the crane.

The present invention provides an indicating device by which the operator for crane may instantly know -the total weight producing a moment arm at the end of the crane boom. A device constructed in accordance with the present invention allows the crane to be more certainly operated with safety by providing instant weight indication regardless of operating conditions. Apparatus is provided wherein the weight producing a moment arm at the end of the boom can be read within plus or minus 2% making it possible to greatly reduce crane tipping, boom failure, damage to material lifted, and in general improve the degree of safety by which cranes can be operated.

As indicated above, the force of primary concern in any crane operation is that force which is applied to the end of the boom and which creates the moment arm, regardless of the length or radius of the boom. Thus, Yto maintain the crane operation Within safe limits, it is necessary to know the instantaneous weight at the end of the boom. This weight would include the weight of the object supported on the crane hook plus all weight acting on the tip of the boom, including the cable, blocks, and other entrained rigging. In accordance with the present invention, a tensiometer is provided in the main hoist line, and is calibrated to read the required weight.

Tensiometers have of course been used in all types of weight supporting devices, such as hoists, boring lines, well drilling, trawling and certainly on cranes. However, none of these -tensiometers have been adapted for use directly in the main hoist line of a crane while the crane is in use. Thus, no device has been provided for accurately measuring within plus or minus 2% the Weight which creates the moment arm at the ends of lthe crane boom.

In accordance with the present invention, a tensiometer is so constructed that it is capable of being used in the main hoist line. In particular, the crane load indicator inclu-des a bottom roller and flexible arresting gear which allows full movement of the main hoist line. By full movement is meant the change in the angle of the main hoist line with respect to the boom as the boom moves upwardly and downwardly, as well as shifting the position of the hoist line over the boom as the line unrolls from the supply drum. This movement is unalected by incorporation of the tensiometer. Moreover the tensiometer can be readily incorporated in existing cranes.

Another feature of the present invention is the provision of a scale for the gauge of the tensiometer which permits the operator to immediately read the weight on the main hoist line without being affected by additions to the boom. Thus, the scale is capable of measuring the weight regardless of the number of lines, i.e., the reading on the scale is unaffected by the number of sheaves used.

Still another advantage of the present invention is that it is readily portable and can be quickly changed from crane to crane if desired. When wire line sizes are the same, the change can be made in a matter of minu-tes.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is a perspective View of a crane boom showing the invention mounted thereon.

FIGURE 2 is an enlarged fragmentary side elevation of the boom and tensiometer illustrated in FIGURE 1.

FIGURE 3 is a sectional view of the invention as illustrated in FIGURE 2 taken along `the line 3 3.

FIGURE 4 is partial transverse sectional view of the invention as illustrated in FIGURE 2 taken along the line 4 4.

FIGURE 5 is a sectional view of the portion illustrated in FIGURE 4 taken along the line 5 5.

FIGURE 6 is a transverse sectional view of the invention as illustrated in FIGURE 2 taken along the line 6 6.

FIGURE 7 is a partial sectional view ltaken along the line 7 7 in FIGURE 1.

FIGURE 8 is a si-de elevation of the weight indicator and support bracket taken along the line 8 8 of FIG- URE 7.

Referring now to the drawings in detail, wherein like numerals indicate like elements, there is shown in FIG- URE 1 a tensiometer designated generally as 10 mounted on a crane boom 12.

As shown, the boom 12 is of conventional structure which includes right and left main elements 14 and 16 joined together by reinforcing cross braces 18. The boom 12 is shown merely for the purpose of better illustrating the invention. It should be understood that any other type of boom structure could be used. The boom structure for purposes of the invention serves only to support the tensiometer in the manner that will be explained below.

As shown, the boom 12 is pivotally connected by pin 20 to a relatively fixed base which may be a truck or trailer, or any other type of supporting structure for a crane boom.

A fast or main hoist line 22 is shown extending above and along the length of the boom 12. The main hoist line 22 is run in and out by operating a drum onto which it is wound and unwound. This, of course, is conventional in the operation of any crane and need not be described in detail. Those familiar with the operation of a crane will recognize that as the line is run in and out, it traverses back and forth over the boom 12. This is because the main hoist line is laid down in a helix on the drum which progressively moves along the axis of the drum until one layer is completed and then moves back in the opposite direction to complete another layer of wound line. The length of traverse depends upon the width of the drum.

The tensiometer 10, which is shown mounted on the main hoist cable 22, is of the three sheave type which measures and monitors the tension in a moving wire line. The structure of the tensiometer 10 plays no part in the present invention. Accordingly, it will not be described in detail. However, any one of several types of well known tensiometers can be used. By way of example and not limitation, the tensiometer 10 can be of the type manufactured by the Martin-Decker Corporation of Long Beach, Calif., and sold under the name Dyna-Line Tensiometer. This type of tensiometer measures and monitors tension-in a moving wire line. It is portable and consists of a deflection type force frame and a hydraulic load cell. The force frame encompasses three sheaves and the moving line is ldeflected as it passes through the sheaves. The force of the deflected line -against the sheaves is then transmitted to the load cell. A hydraulic gauge, a needle and cooperating scale is connected to the tensiometer to read the output.

In the present invention, gauge 24 is shown mounted on the boom 12 and is connected to the tensiometer by the hydraulic line 26. A second hydraulic line 28 is connected to a pressurized source of hydraulic uid and provides the hydraulic iluid for operation of the tensiometer 10. An oversize volume adjust chamber can be connected to line 28 to overcome temperatures on the hydraulic system so that manual controls may be adjusted to have the start point coincide with the system temperature. The gauge 24 includes a rotating pointer 30 which is responsive to the hoist line 22. The gauge 24 also includes a dial face 32 on which is provided a number of scales which are calibrated to read the output of the tensiometer 10 in pounds or multiples thereof.

As best shown in FIGURE 2, a plate 34 is mounted directly to the bottom of the tensiometer 10. At either end of the plate 34 are blocks 36 and 38 which support bearings 40 and 42 within which is mounted the shaft 44. Shaft 44 is preferably one inch in diameter and made of steel, although those skilled in the art will recognize that other diameters and other types of metals may be used. An elongated roller 46 is rotatably mounted on the shaft 44 intermediate two collars 48 and l50 which are iixed on the shaft by means of set screws (not shown). The collars 48 and 50 x the roller 46 in axial position on shaft 44.

-By way of example but not of limitation, the shaft 44 may be approximately eight to ten inches in length, the -roller ive to six inches in length and three inches in diameter. The roller of course has a one inch bore therethrough for receiving the shaft. Although other materials m-ay be used, the roller 46 is preferably made of a polymer or other type of resilient plastic which is capable of withstanding and absorbing a large amount of the shock imparted to the tensiometer when it strikes the boom as will be explained hereinafter.

As shown in FIGURES 3 and 4, the roller 46 rests on a plate 52 which is fixed to the top of the structural elements and 16 of the boom 12. Plate 52 provides a surface upon which the roller 46 may roll when the hoist cable permits the tensiometer to rest against the boom. There may be angles of the boom at which the cable 22 will be moved away from the top of the boom by a distance sutiicient to pull the tensiometer roller 46 out of contact with the plate 52. At other angles the roller `46 is in contact with the plate y52.

Plate 52 includes a pair of anges 54 and 56 which extend from the sides thereof and overlie the sides of structural elements 14 and 16. Each of the flanges 54 and 56 is provided with a set screw 58 and 60 which is threadedly engaged therein. By tightening the set screws 58 and 60, the plate 52 can be clamped to the elements 14 and 16. Additional clamping is provided by the clamping plates l62 and 64 which underlie the top anges of the structural elements 14 and 16 and are bolted to a side flange 66 of the plate 52 by means of threaded fasteners 68. Thus, the clamping plates 62 and 64 assist in holding the plate 52 against the structural elements 14 and 16. The method described above for clamping the plate 52 to structural elements 14 and 16 has been designed so that it will -t almost any crane boom presently being manufactured.

The widths of plate 52 should be at least as wide as the overall distance between the bearings 40 and 42 which support the roller 46. This is necessary to assure that the roller will always make contact with the plate since it traverses across the plate in a slight curve `as indicated by the arrow thereon.

As best shown in FIGURES 2 and 3, the tensiometer 10 is retained in longitudinal position on the boom 12 by means of an arresting gear 70 which includes an arm 72 4 connected to a universal joint 78 by any conventional means, such as a butt weld. Joint 78 is connected to one end of the arresting gear rod 80 which in turn is connected at its opposite end to the universal joint 82. The method of connecting the rod 80 to the universal joint 78 and 82 can be any conventional means, such as a butt weld. Universal joint 82 is connected to a plate 84 also by a butt weld or some other conventional connecting means.

As best shown in FIGURE 6, plate 84 is ixed to plate -86 which in turn is fixed to bracket 88.

Bracket 88 retains the plate 84 on the boom 12 by means of a pair of fasteners 90 and 92 which extend through flanges 94 and 96 and clamping plates 98 and 100. Fasteners 90 and 92 thereby clamp the bracket 88 against the structural elements 14 and 16 of the boom 12.

Also supported on the bracket 88 is a cable guide 87 comprising a pair of uprights 102 and 104 and a cross bar 106 all joined together and tixed to the bracket 88. Preferably, the uprights 102 and 104 are bent inwardly at their bottom and welded to the bracket 88. Further, the plate 84 is preferably xed to the cross bar 106, as by welding, to provide additional support.

The cable guide 87 prevents the line hoist 22 from becoming fouled in the arresting gear during operation.

The arresting gear 70 prevents the tensiometer from following the hoist line 22 as it is let out or drawn in along the boom 12. The provision of the universal joints 78 and 82 allows the arresting gear to move in all directions as the tensiometer 10 traverses back and forth across the boom and as it moves up and down due to changes in angle between the boom 12 and the hoist line 22.

As is apparent from FIGURES 2 and 3, the joint 78 includes mutually perpendicular axes of rotation 79, `81, extending generally perpendicular to the longitudinal axis of the boom 12. The axis 79 extends in a direction generally normal to the planar surface of the plate y52, and the axis 81 extends general parallel to that surface. Similarly, the joint 82 includes mutually perpendicular rotational axes 83 and 85, also generally perpendicular to the longitudinal axis of the boom 12. The axis 83 extends in a direction generally normal to the planar surface of the plate 52, and the axis 85 is generally parallel to that surface.

Since substantially all boom type cranes are operated from cabins where the operator may look directly up the boom, it is desirable to place the weight indicator directly on the boom. For this purpose, a universal bracket has been provided wherein the gauge 24 is mounted on a bracket 108 which extends upwardly from a Z-shaped mounting plate 110 at an appropriate angle which allow the operator to view the same. Mounting plate 110 is Ibolted to structural member 14 of boom 12 as shown in FIGURES 7 and 8. A U-shaped member 112 is positioned immediately below the outwardly extending flange of Z-shaped mounting plate 110. Another Z-shaped mounting plate 114 is bolted to the bottom of structural member 14 as shown so that it too has a flange extending in the same direction as the flange of Z-shaped mounting plate 110. The U-shaped member 112 is held between these members by bolts 116 and 118. The function of U-shaped member 112 is to cooperate with the Z-shaped mounting plates 110 and 114 to rigidify and prevent large vibrations of the gauge 24. Thus, the operator can always read the gauge even during the movement of the crane of the boom 12.

As best shown in FIGURE 1, the dial 32 includes a plurality of lines thereon. The lines are subdivided and each division represents a thousand pounds. The outer dial lines are used when the crane has six parts of line at the end; the next inner line is for use when the crane has four parts of line; the third line is for two parts of line; and the inner line is for one part of line. O-f course, additional lines or less lines could be added as needed.

The present invention may be embodied in other speciiic forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specication as indicating the scope of the invention.

I claim:

1. A crane load indicator comprising a tensiometer operatively associated with the load cable extending along the crane boom, a plate dening a planar surface mounted to said Ihoorn at a position immediately below said tensiometer, an elongated roller mounted on a Shaft, said shaft being supported in bearings, said bearings being fixed to said tensiometer, the longitudinal axis of said roller being approximately aligned with the axis of said cable, arresting means fixing said tensiometer position where its roller makes rolling contact with said plate, said arresting means including a flexible connector between said tensiometer and said boom for permitting said tensiometer to traverse laterally of said 'boom and to move generally vertically with respect to said boom so that said roller is out of contact with said plate, said arresting means including an arm, a iirst universal joint coupling the rst end of said arm to said tensiometer, and a second universal joint spaced from said lirst universal joint and coupling the second end of said arm to said boom.

2. Apparatus for measuring a load on a crane having a boom and load cable extending along the boom, comprising a tensiometer adapted to measure the tension in the load cable, a Iplate adapted to be coupled to said boom, a roller rotatably iixed on said tensiometer, and arresting means for retaining said tensiometer in a longitudinal position with respect to the boom wherein said roller makes rolling contact with said plate, said arresting means comprising an elongated arm, a first coupling member coupling said tensiometer to a first end of said arm, said coupling `member providing axes of rotation extending generally normally and generally parallel to said plate, and a second coupling member adapted to couple a second end of said arm to the boom, said second coupling member providing axes extending in directions generally normal and generally parallel to said plate. v

3. Apparatus in accordance with claim 2 wherein said tensiometer includes an indicating .gauge with a plurality of scales thereon calibrated to read the weight of the load at the end of the boom.

4. Apparatus in accordance with claim 2 including a cable guide adapted to be mounted on the boom, said second coupling being coupled to said cable guide.

5. Apparatus in accordance with claim 2 wherein said roller comprises an elongated roller mounted on a shaft, said shaft being supported in bearings, support means fixing said bearing to said tensiometer, said roller being mounted so that its longitudinal axis is approximately aligned with the axis of the cable when said tensiometer is operatively associated with the cable.

References Cited UNITED STATES PATENTS 2,081,665 5/1937 Greene 73-144 2,121,870 6/1938 yGreene 73-144 X 2,183,817 12/1939 Mathey 73-144 2,310,597 2/1943 Raphael 73-144 RICHARD C. QUEISSER, Primary Examiner.

JERRY W. MYRACLE, Assistant Examiner. 

